Java EE (Java Enterprise Edition) General Discussion

Hi all,

Long term developer - newish to JSF - I've come across the same issue as many other people relating to EL expressions in UIComponent attributes, but can't find an answer (e.g http://forum.java.sun.com/thread.jspa?forumID=427&threadID=782895 is almost the same question but is unanswered).

The problem is this: -

I believe UIComponent.getAttributes() implements the weirdest Map I've ever used. Yes, I've read the Java Docs and bits of the various specs - but it doesn't help me understand where my EL component attributes go.

I don't believe the implementations of UIComponent.getAttributes() can be the best solution - I've tried a number of different versions/impl's and they all do similar things... I'm obviously missing something - help!

Details: - If I have a JSF as follows: -

-----
<h:form >
<c:set var="variable" value="TODAY"/>
<h:commandButton actionListener="#{bugbean.action}">
<f:attribute name="attr1" value="constant-string" />
<f:attribute name="attr2" value="#{variable}" />
</h:commandButton>
</h:form>
-----
and in the backing bean "bugbean" I have the following...

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public void action(ActionEvent event){

System.out.println("JSF <f:attribute/> test started");

UIComponent comp = event.getComponent();

Map stuff = new HashMap();
stuff.putAll(comp.getAttributes());
System.out.println("UIComponent.getAttributes() as a Map ["+stuff+"]");

System.out.println("UIComponent.getAttributes().size() reports ["+
comp.getAttributes().size()+"]");

System.out.println("UIComponent.getAttributes().get(\"attr1\") reports ["+
comp.getAttributes().get("attr1")+"]");

System.out.println("UIComponent.getAttributes().get(\"attr2\") reports ["+
comp.getAttributes().get("attr2")+"]");
}
-----
I get the following output: -

-----
JSF <f:attribute/> test started
UIComponent.getAttributes() as a Map [{attr1=constant-string, com.sun.facelets.MARK_ID=271e6d86}]
UIComponent.getAttributes().size() reports [2]
UIComponent.getAttributes().get("attr1") reports [constant-string]
UIComponent.getAttributes().get("attr2") reports [TODAY]
-----
Note:
1) UIComponent.getAttributes().size() reports 2. That's the "com.sun.facelets.MARK_ID" (added by JSF) and "attr1" elements of the Map.
2) There is no mention of "attr2" - but I know I put it in there...
3) I can call UIComponent.getAttributes().get("attr2") and guess what - hey presto - it works and I get my value! It appears that UIComponent.getAttributes() just hides my EL attributes somewhere else... but where and why?

The issue I have is simple: -
I have never used a Map that reports a size of "x", but actually contains "hidden" elements that I can't find unless I already know the name of the element. And the weird behavior depends only on the "value" of the element being an EL expression.

I have read the many, many threads on many sites relating to the JSF 1.1 spec being "fluffy" over the implementation of UIComponent.getAttributes() - it hasn't helped me understand what is going on.

Have I missed something or is this just the way it's supposed to work?

Thanks in advance...